CMOS cross-coupled differential voltage controlled oscillator

Abstract

A CMOS cross-coupled differential voltage controlled oscillator is provided with a pair of oscillator outputs. The oscillator includes a current control unit, a first cross-coupled differential pair, an inductor unit, a capacitor unit, a second cross-coupled differential pair and a voltage controller. The current control unit is coupled between a relatively-high voltage and a relatively-low voltage. The first cross-coupled differential pair, the inductor unit, the capacitor unit and the second cross-coupled differential pair are coupled between the pair of oscillator outputs. According to the present invention, the inductor unit is provided with a midway node. The voltage controller is coupled and powered by the midway node.

1 . A CMOS cross-coupled differential voltage controlled oscillator provided with a pair of oscillator outputs, comprising:
 a current control unit coupled between a relatively-high voltage and a relatively-low voltage;   a first cross-coupled differential pair, an inductor unit, a capacitor unit and a second cross-coupled differential pair are coupled between said pair of oscillator outputs in parallel and cascaded between said current control unit and said relatively-high voltage, wherein said inductor unit includes a shared node; and   a voltage control unit coupled between said shared node and said relatively-low voltage, wherein said voltage control unit controls said capacitor unit according to a plurality of voltage control signals and then outputs signals to said pair of oscillator outputs.   
   
   
       2 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 1 , wherein said inductor unit has a first inductor and a second inductor serially coupled between said pair of oscillator outputs and a coupling node of said first inductor and said second inductor is said shared node. 
   
   
       3 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 1 , wherein said inductor unit is a single inductor and the location near the middle of said single inductor is said shared node. 
   
   
       4 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 1 , wherein said capacitor unit has a plurality of switch capacitor sets coupled between said pair of oscillator outputs in parallel. 
   
   
       5 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 4 , wherein each said switch capacitor set has a first capacitor and a second capacitor serially coupled between said pair of oscillator outputs, a coupling node of said first capacitor and said second capacitor is a bias point. 
   
   
       6 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 5 , wherein said voltage control unit has a plurality of buffers for coupling said voltage control signals to said bias points of said switch capacitor sets, respectively. 
   
   
       7 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 1 , wherein said first cross-coupled differential pair is a pair of cross-coupled PMOS field effect transistors. 
   
   
       8 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 1 , wherein said second cross-coupled differential pair is a pair of cross-coupled NMOS field effect transistors. 
   
   
       9 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 1 , further comprises a capacitor coupled between said shared node and said relatively-low voltage. 
   
   
       10 . A CMOS cross-coupled differential voltage controlled oscillator having a pair of oscillator outputs, comprising:
 a current control unit coupled between a relatively-high voltage and a relatively-low voltage;   a first cross-coupled differential pair, an inductor unit, a capacitor unit and a second cross-coupled differential pair are coupled between said pair of oscillator outputs and cascaded between said current control unit and said relatively-low voltage, wherein said inductor unit includes a shared node; and   a voltage control unit coupled between said shared node and said relatively-high voltage, wherein said voltage control unit controls said capacitor unit according to a plurality of voltage control signals and then outputs signals to said pair of oscillator outputs.   
   
   
       11 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 10 , wherein said inductor unit has a first inductor and second inductor serially coupled between said pair of oscillator outputs and a coupling node of said first inductor and said second inductor is said shared node. 
   
   
       12 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 10 , wherein said inductor unit is a single inductor and the location near the middle of said single inductor is said shared node. 
   
   
       13 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 10 , wherein said capacitor unit has a plurality of switch capacitor sets coupled between said pair of oscillator outputs in parallel. 
   
   
       14 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 13 , wherein each said switch capacitor set has a first capacitor and second capacitor serially coupled between said pair of oscillator outputs, a coupling node of said first capacitor and said second capacitor is a bias point. 
   
   
       15 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 14 , wherein said voltage control unit has a plurality of buffers for coupling said voltage control signals to said bias points of said switch capacitor sets, respectively. 
   
   
       16 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 10 , wherein said first cross-coupled differential pair is a pair of cross-coupled PMOS field effect transistors. 
   
   
       17 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 10 , wherein said second cross-coupled differential pair is a par of cross-coupled NMOS field effect transistors. 
   
   
       18 . The CMOS cross-coupled differential voltage controlled oscillator of  claim 10 , further comprises a capacitor coupled between said shared node and said relatively-low voltage.